1. Field of the Invention
The present invention relates to a method for recovering and utilizing an oil by regeneration treatment using a reducing water generated at a cathode side in electrolysis, as a link in recycling of a waste edible oil.
2. Description of the Related Art
Waste edible oils have conventionally been mainly subjected to combustion treatment, and only a part of waste edible oils has merely been utilized as a raw material for soaps or paints. However, in recent years it is pointed out the danger of de novo formation of dioxine originated from sodium chloride in the course of combustion, and it has been the recent trend that it is difficult to easily conduct combustion treatment of waste edible oils unavoidably contaminated with sodium chloride from food materials. In addition, Food Recycle Rule will be started in the year of 2001 from the standpoint of resource protection. Thus, it has been required to conduct recycling in any form regarding waste edible oils.
From the above standpoint, a method of forming a light-oil alternate fuel has recently been developed as a method of recycling a waste edible oil, other than the conventional method of forming soaps or paints. This method comprises adding methanol and a trace amount of a catalyst to a waste edible oil, heating the resulting mixture to conduct reaction, thereby forming methyl ester and glycerin. Methyl ester from which glycerin has been removed is purified (washed in water and dehydrated) and filtered to obtain a light-oil alternate fuel. This method has the advantages that time required for the overall steps is several hours, 95 liters of products can be recovered from 100 liters of a waste edible oil, and yield is very high. However, this method has the disadvantage that it is applied to only vegetable oils. Thus, this method does not conform to the actual circumstances that many waste oils contain animal oils. Further, this method needs construction of an efficient recovery system of waste edible oils as a raw material or an efficient supply system of fuels produced.
Many methods of regenerating waste edible oils and recovering and utilizing the same as an edible oil are proposed. However, cost increases in order to obtain a high quality oil, and for this reason, there has conventionally been no method that is practically conducted. In recent years, a method of filtering under reduced pressure heated waste edible oils using a paper-made filter containing active clay or a method of subjecting the waste edible oils to filtration treatment using active carbon have been developed as described in Japanese Patent Application Laid-open No. 2000-201621. Those methods can remove coloring components contained in oils, and as a result, the oil that is clear in appearance is obtained. Therefore, those methods are used to treat oils in which deterioration does not proceed and to reutilize the treated oils. However, those methods have low effect to decrease AV (acid value) that is a measure of deterioration of fats and oils. Therefore, in case that it is intended to treat waste edible oils having increased deterioration and therefore having high AV value, it is difficult in such methods to obtain products reaching an allowable level as an edible oil. Further, there is the problem in that uncomfortable odor remains in the treated oils. Thus, there remain various problems to be improved in order to promote the wide spread of such methods.
The present invention has been made in view of the above, and an object of the present invention is therefore to provide a treatment method of a waste oil, that can effectively produce glycerin even from waste oils containing animal oils.
Another object of the present invention is to provide a treatment method of a waste edible oil, that can obtain a re-utilizable edible oil even from a waste edible oil in which deterioration proceeds.
In order to solve the above problems, according to the present invention, there is provided a treatment method of a waste oil, which comprises adding a strongly alkaline water obtained by electrolyzing water containing sodium chloride to a waste edible oil and/or fossil fuel waste oil, and extracting natural glycerin or synthetic glycerin by chemical reaction.
According to the present invention, there is provided a treatment method of a waste edible oil, which comprises electrolyzing an aqueous solution having an electrolyte such as sodium chloride in an electrolytic cell, mixing a strongly alkaline reducing water generated at a cathode side of the electrolytic cell with a waste edible oil under ordinary temperature condition, and conducting oil/water separation, thereby purifying the waste edible oil to an extent such that it can be edible.
In the above-described treatment method, the electrolyte used is preferably one member selected from the group consisting of sodium chloride, sodium sulfate, sodium carbonate, potassium carbonate and calcium hydroxide.
Further, the treatment method comprises:
a method having a system comprising an electrolytic cell, a reaction tank and an oil/water separation means;
a method comprising ultraviolet irradiation or a combination of ultraviolet irradiation and addition of divalent iron ion in order to increase removability of peroxide; and
a method having a system comprising a reservoir tank for waste edible oil and a reaction tank, each having an ultraviolet irradiation means arranged therein, or a system comprising a reservoir tank for waste edible oil having an ultraviolet irradiation means, and a reaction tank having an ultraviolet irradiation means and a divalent iron ion supply means arranged therein.